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Current Emergency Information

2025 Moss Landing Vistra Power Plant Fire

Webpage updated 09/03/2026 03:19 PM

Update: Characterization and Screening-Level Risk Evaluation Report Available

Commonly referred to as the Preliminary Environmental Assessment (PEA) Equivalent Report

Prepared by Terraphase Engineering, dated June 22, 2026

State agency partners reviewed the preliminary report and presented their initial findings to the County of Monterey Board of Supervisors on March 17, 2026. Terraphase then prepared the revised report dated June 22, 2026. The County does not expect further revisions.

Report Conclusions

Terraphase concluded that:

  • Chemicals measured in the sampled off-site soil, sediment, and surface water do not indicate lasting conditions expected to pose an unacceptable risk to people or ecological receptors.
  • For purposes of the risk evaluation, Terraphase used conservative, health-protective assumptions and treated measured chemical concentrations as if they were related to the fire.
  • Some nickel concentrations in sediment exceeded ecological screening levels in Hester Marsh and the Mosquito Abatement Observation Area. Terraphase attributed these results to natural variability and marsh conditions rather than lasting fire-related impacts.
  • No further human-health or ecological-risk evaluation, off-site investigation, or response action is warranted at this time for the sampled locations and environmental media.

These conclusions do not apply to conditions within the power plant property, groundwater, unsampled areas, or broader watershed conditions that may be addressed through separate regulatory work.

The report also reviewed air-monitoring and air-sampling data collected by U.S. EPA and CTEH. Terraphase stated that the limited number, generally low magnitude, and short duration of metals-in-air detections above screening levels did not indicate sustained exposure at levels of health concern.

Questions about the report or Terraphase’s conclusions may be submitted to EHB for referral to Terraphase: EHInfo@countyofmonterey.gov

State Agency Review of Report

The following agencies reviewed both the preliminary and revised reports:

Questions about each agency’s comments may be directed to:

U.S. EPA did not participate in the review because its oversight role is focused on on-site battery-removal activities. The County directed the off-site community sampling, and the participating CalEPA agencies reviewed the reports.

What happens next?

Publishing the revised report and state agency comments completes the County’s planned Community Sampling Plan and PEA-equivalent review process.

Completion of this County-directed process does not end other investigations or regulatory work. Separate work may continue regarding:

  • Groundwater;
  • Broader watershed or Elkhorn Slough conditions; and
  • Follow-up recommended or required by state agencies.

Separate work continues within the power plant property

Vistra’s battery removal and the related demolition, treatment, and preparation of batteries for recycling or disposal remain under U.S. Environmental Protection Agency oversight. Information and updates are available through the U.S. EPA Moss Landing Vistra Battery Fire response webpage:  https://www.epa.gov/ca/moss-landing-vistra-battery-fire

Latest News

EPA Completes Air Monitoring Near Moss Landing Vistra Battery Fire

Post Date:01/21/2025 3:59 PM

On January 20, the U.S. Environmental Protection Agency (EPA) concluded supplemental air monitoring in the vicinity of the Vistra Energy battery power storage facility fire in Moss Landing, CA. Results for hydrogen flouride and particulate matter showed no risk to public health throughout the incident, and smoke from the facility has greatly diminished. The EPA demobilized air monitoring operations after consultation with the Monterey County Incident Command for the Vistra fire.

EPA began monitoring for hydrogen flouride, a highly toxic gas produced by lithium-ion battery fires, and for particulate matter after the fire began on January 16. The request for air monitoring came from Monterey County. As part of the multi-agency emergency response, EPA installed a total of nine monitoring stations shortly after the fire started. Two monitoring stations were located at the facility and four just outside the facility, including one at Moss Landing. Three monitoring stations were located in communities due east of the fire, to the south near Castroville, and to the north in the vicinity of Moss Landing Middle School. Monitoring stations were sited to account for changes in wind direction and potential drift to nearby communities.

EPA’s monitoring showed concentrations of particulate matter to be consistent with the air quality index throughout the Monterey Bay and San Francisco Bay regions, with no measurements exceeding the moderate air quality level. Hydrogen flouride gas was measured at one second intervals and there were no exceedances of California’s human health standards.

In addition to EPA’s monitoring, Vistra Energy brought in a third-party environmental consultant with air monitoring expertise, right after the fire started, to conduct roaming and fixed air monitoring in communities. Air monitoring stations have been installed where EPA’s stations had been located to continue air monitoring as the response progresses. An air monitor location map is located at the County’s incident website. The Monterey Bay Air Resources District also monitors particulate matter through their regulatory air monitors and wildfire smoke sensors.

Throughout the response, EPA has shared air monitoring data with state and local officials to inform public health decisions, including North Monterey County Fire, Monterey County Environmental Health, and Cal Office of Environmental Health Hazard Assessment.

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Timeline of Environmental and Public Health Response 

More Information

Stay Informed

To receive ongoing updates, residents are encouraged to register for alerts at Register | Portal Registration or visit Emergency | County of Monterey, CA. To check your zone, please visit Genasys Protect.

US EPA - Moss Landing Vistra Battery Fire Response

See Yellow Smoke?

Yellowish or brownish smoke can occur during turbine start-ups at the facility. When turbines start, emissions are temporarily higher than during steady operation—similar to starting a car engine. This is a normal, permitted part of facility operations. More information is available here

Concerns or Complaints?

You can submit a report to the Monterey County Health Department's Environmental Health Bureau online at http://www.mtyhd.org/mosslanding-concern-form or by leaving a voice message at 831-755-4505.